For a few years now we have been trying to grow potatoes at 1500 ft in Haiti. Our climate is quite mild and I see no reason in terms of climate that they shouldn’t grow but every time we try they grow to about 20cm and then just stagnate and eventually the top dies back. Under the soil we find dime sized potatoes. Last year we tried them in our best soil and nothing improved. Could it be too wet? Our drainage is good so I doubt that but I’m grasping for a solution here. What should I look for for the source of this problem?
Have you had a chance to check your soil for PH and other soil nutrients yet? Many tropical and sub tropical areas have acidic soils the some plant varieties don’t do well in. Soil amendments and adding an abundant of organic matter can help with that.
Rose. We need more information to answer this question. We are likely going to need pictures. There could be fertility or excessive acidity which often go together, blight, nematodes, droughty (lack of consistent rain or irrigation), planting too deep, fusarium, etc. And we need to know if the top dies back a little at a time as per blight or completely and how long before the top dies back which if the potato has run a normal crop cycle could be a natural process and therefore the problem is either nematodes, drought or fertility/acidity.
I’ll try to grow them again this year and take some pictures as they die back.
I have a couple of new clues though. First, I did a pH test on the spot that I was growing them in last year and it was 6.5 so pH seems to be fine. We’re blessed to be growing in karst soil. Second, one of our neighbours told us that years ago a foreigner brought in a variety of potatoes that would grow big potatoes but they have since lost them. All he’s aware of now is the little tiny ones that their currently growing. That make me think that disease might be a factor.
Also, I do have experience with potatoes in particular. We grew tons of them in Canada so this just mystifies me. It also rain a lot here (2.5m of rain annually) so drought isn’t a factor.
Hey, I’m no potato specialist but I would think a fungal disease would be likely. 2.5m of rain is A LOT of rain…
The fact they died back… Might indicate a root/soil borne disease, whereas if foliage looked sick it could be a foliar disease…
Fungal diseases generally thrive in warm and moist conditions.
Again, maybe try a disease identification guide or ask a local agronomist… A bit like medical things, agronomists get used to the common problems in their area. Doctors in West Africa for example quickly diagnose malaria and know the treatments by heart… Whereas many qualified doctors in the other parts of the world, while they would have heard of malaria wouldn’t be experienced in treating it.
If it is fungal… A lot of fungicides need to be sprayed preventatively. They kill the spores to prevent the plant getting infected. Waiting until the plants show symptoms and are sick isn’t going to work.
To put it into perspective with other crops… tomatoes in some parts of the humid tropics need to be sprayed frequently. A lot of wheat crops would receive a dose of fungicides to protect the flag leaf… I recall a barley crop where the buyer stipulated that it had to be grown using 3 fungicide applications. I think it was for HobNobs or Digestive biscuits or something. Anyhow, something like Mancozeb could work and is probably registered for potatoes but you should double check. I believe you can get products that you can apply at planting or on the seed potatoes that could help if instead its caused by a soil born disease.
In general, if plants looks sick, pull up some sick ones and cut them open - the roots, stems, etc… BEFORE they die completely… then pull some healthy ones and check them out and look for differences and if there are differences take photos… All that can give good info that can help diagnose it. It’s basically a plant autopsy…
At times people don’t want to pull up their crops if they have only planted a few but it’s worth it in the long run to work out what the issue with them is.
Sounds like its been a problem for multiple people in multiple years.
Alternatively, apart from using fungicides (soil and or foliar) you definitely want to look for resistant varieties (what type did those others grow!) If in doubt try a bunch! If you suspect it is disease try spacing the plants further apart to lower humidity by increasing air flow around the foliage helping them dry faster after rain and look to rotate and avoid planting in places you know they were diseased…
Or you want to grow other crops. There are often good reasons why farmers specialize in a few main crops in certain areas… Because they are well adapted… And I reckon God in his wisdom will have provided them with suitable plants for carbs, protein, oil crops, etc that, with hard work, can produce well - that said, If we aren’t local we might not be used to cooking and eating them, but that’s another matter.
All the best with it.
Dave you are one of the best repliers on these posts. Great point that when you see the blight it is almost always too late, particularly when you see it early in the growing season–your crop will soon be devastated by it if blight starts in the first half of the growing season and spraying will only buy you a week or two of protections in most cases. Spraying when there is so much rain is not all that effective. I always teach people about how to grow tomatoes in the rainy season and the blight issue is the same in the rainy season. If you don’t want blight then get fresh clean cut grass mulch with no dirt in it (you can’t rake leaves or grass off the ground and use for mulch) and put it 2 or 3 inches thick everywhere and then you don’t dare enter the patch when the plants are wet to do anything until they are completely dry. And you plant at wide spacing and best to plant along a path or field edge so you get the air flowing rapidly past and through your plants. You can plant something between your potato plants as long as it is a very low profile plant. Your lowest profile plants are purslane, lettuce (not sure if it grows there without bolting), baby bok choy. I would consider cucumber or muskmelon or watermelon as an intercrop but push the vines away from the potatoes unless the weather turns unseasonably dry or you are 2 or 3 weeks from harvest of the potatoes and then it does not matter. You have to have airflow and heavy mulch or you will be in trouble again. You can also pick off leaves that are developing blight (only makes sense during the first 3 weeks of growth) if you have a bag to put them in and only when it is dry.